Analyze Invitation Letter

1. Purpose : To invite a student, Jono to come to the preparation for his school anniversary celebration.
2. Salutation/greeting : Dear Jono
3. Content : There will be a preparation for the school anniversary celebration on Saturday,  9th May 2015 at 4 p. m. and will be held at School Meeting Room.
4. Date, time, and place : On Saturday,  9th May 2015 at 4 p. m. and will be held at School Meeting Room
5. Signature : not listed

This is a informal invitation letter because there isn't signature and the greeting is informal.